S-antigen-specific T cells play a primary role in the induction of experimental autoimmune uveitis (EAU) and pinealitis (EAP), a severe inflammatory disease of the uveal tract, retina and pineal gland. Antigen-specific T cells are generated in Lewis rats by injection of S-antigen or peptide M, a synthetic octadeca peptide, which corresponds to the amino acid sequence of the pathogenic site of bovine and human S-antigen. EAU also develops after the passive transfer of activated S-antigen-specific T cell lines or peptide M-specific T cell lines and clones. Moreover, in some types of uveitis in humans, in vitro T cell mediated responses to S-antigen can be elicited. In this proposal we will refine and expand our previous efforts regarding the generation of rat T cell clones specific for peptide M. Our studies will further define the epitopes recognized by the clones and their uveitogenicity. Monoclonal antibodies raised against MHC class II I-A and I-E determinants will be used to define MHC-restriction of EAU and skin DTH reactions as shown in experimental autoimmune encephalomyelitis. In addition, irradiatied T cell lines and clones will be used to protect against induction of EAU as shown in our preliminary results. To further characterize the T cells capable of mediating EAU, T cell clones will be established from susceptible x resistant (Lewis x DA) F1 rats. The clones will be analyzed for reactivity to S- antigen (404 amino acids) and to 23 synthetic peptides corresponding to its entire amino acid sequence, in order to determine additional pathogenic sites. Clonal studies of mechanisms of MHC-restriction of EAU in F1 animals will allow for the determination of association of haplotype with S-antigen epitopes and functionally distinct T cells. The establishment and characterization of peptide M-specific clones provides a new method to study the pathogenic mechanisms involved in T cell mediated autoimmune diseases such as EAU. Such studies may ultimately prove valuable in elucidating pathogenic mechanisms in human uveitic conditions and may allow for the development of specific immunotherapeutic reagents for the treatment of uveitis.